This invention relates to bezel apparatus for a display screen of a display device, and more particularly to a bezel containing an arrangement of radiation emitter and detector pairs for utilization in a touch input computer display system, and a method for assemblying the bezel apparatus to the display device.
One type of interactive computer system permits an operator to enter information into the computer by selectively touching points on the screen of a computer monitor or display device, such as a cathode ray tube (CRT), upon which is displayed relevant information. One such touch input system provides an arrangement of radiation emitter and detector pairs, for example a plurality of light emitters (typically in the infrared range) arranged along one vertical side and one horizontal side of the display screen, and a plurality of detectors arranged along the other vertical and horizontal sides. The resulting rectangular arrangement of emitter and detector pairs produces a corresponding light beam grid over the display screen which, when interrupted by the operator's finger or a pointer, permits the touched screen location to be calculated by the computer and data related to the information then displayed at the touched screen location to be entered into the computer.
One manner of supporting the arrangement of infrared emitters and detectors is to enclose the arrangement within a rectangular bezel bordering the display screen or CRT face, the bezel being of a material transparent to infrared radiation and often referred to as a touch screen bezel. The arrangement is fixed within the touch screen bezel such that the emitters and detectors are in predetermined spatial relation to the CRT face when the bezel is in predetermined position in relation to the CRT face. Accordingly, it may be appreciated that the accurate determination of the location of each point touched on the CRT face depends in part upon the accuracy with which the touch screen bezel is positioned upon the CRT face. The mounting of the CRT and the touch screen bezel to the assembly's chassis for producing such accurate positioning, however, is somewhat hampered by the fact that the face of a typical CRT may not have been accurately positioned relative to its mounting points when the CRT was manufactured.
A touch screen bezel is normally mounted to the display system chassis in fixed position determined by the requirement that the bezel be precisely aligned with other housing parts attached to the chassis. When the CRT is mounted to the chassis, the position of the CRT face may be skewed or orthogonally displaced with respect to the precisely fixed touch screen bezel. This problem is typically overcome by adjusting the position of the CRT in the chassis, usually employing a fixture for implementing such adjustments, with the expectation that the bezel will properly seat against the CRT face when the bezel is mounted to the chassis in its fixed position after CRT position adjustments have been completed. Such mounting adjustments require utilization of additional parts and assembly time, and are subject to error resulting in inaccuracies in the seating of the touch screen bezel to the CRT face.